I was going to write that plastics has to be bogger all in weight, but it is 100 kg per person and year in Europe and 200 kg in the US, which is kinda surprising.
There has to be due to industrial or commercial usage right? I mean, I would be surprised if I used more than even 10 kg of plastics per year. That is like 1000s of plastic bags, and I and most people use paper bags anyways.
Plastics take decades centuries to degrade, and most of that degradation is physical - it gets degraded to microplastics. As soon as it's in a landfill where it's not in motion or exposed to sunlight, it's essentially conserved for human lifetime cycles.
Until too much water makes it into the landfill, creates an acid with other mixed materials (like cardboard glues, household cleaners) and then leaches the acids and plastic and heavy metal into the aquifer.
Most landfills near me with liners made in the last 30 years have acid problems and liner breaches
Still releases fossil-origin CO2, we can't afford that for global warming reasons. In a landfill the CO2 remains trapped.
Agree on your reduction point, that is long overdue but will only happen with significant governmental regulations.